std.dwarf: implement basic DWARF 5 parsing

DWARF 5 moves around some fields and adds a few new ones that can't be
parsed or ignored by our current DWARF 4 parser. This isn't a complete
implementation of DWARF 5, but this is enough to make stack traces
mostly work. Line numbers from C++ don't show up, but I know the info
is there. I think the answer is to iterate through .debug_line_str in
getLineNumberInfo, but I didn't want to fall into an even deeper rabbit
hole tonight.

1 files changed, 52 insertions, 0 deletions

diff --git a/lib/std/dwarf/FORM.zig b/lib/std/dwarf/FORM.zig
new file mode 100644
index 0000000000..eb50c1dc93
--- /dev/null
+++ b/lib/std/dwarf/FORM.zig
@@ -0,0 +1,52 @@
+pub const addr = 0x01;
+pub const block2 = 0x03;
+pub const block4 = 0x04;
+pub const data2 = 0x05;
+pub const data4 = 0x06;
+pub const data8 = 0x07;
+pub const string = 0x08;
+pub const block = 0x09;
+pub const block1 = 0x0a;
+pub const data1 = 0x0b;
+pub const flag = 0x0c;
+pub const sdata = 0x0d;
+pub const strp = 0x0e;
+pub const udata = 0x0f;
+pub const ref_addr = 0x10;
+pub const ref1 = 0x11;
+pub const ref2 = 0x12;
+pub const ref4 = 0x13;
+pub const ref8 = 0x14;
+pub const ref_udata = 0x15;
+pub const indirect = 0x16;
+pub const sec_offset = 0x17;
+pub const exprloc = 0x18;
+pub const flag_present = 0x19;
+pub const strx = 0x1a;
+pub const addrx = 0x1b;
+pub const ref_sup4 = 0x1c;
+pub const strp_sup = 0x1d;
+pub const data16 = 0x1e;
+pub const line_strp = 0x1f;
+pub const ref_sig8 = 0x20;
+pub const implicit_const = 0x21;
+pub const loclistx = 0x22;
+pub const rnglistx = 0x23;
+pub const ref_sup8 = 0x24;
+pub const strx1 = 0x25;
+pub const strx2 = 0x26;
+pub const strx3 = 0x27;
+pub const strx4 = 0x28;
+pub const addrx1 = 0x29;
+pub const addrx2 = 0x2a;
+pub const addrx3 = 0x2b;
+pub const addrx4 = 0x2c;
+
+// Extensions for Fission.  See http://gcc.gnu.org/wiki/DebugFission.
+pub const GNU_addr_index = 0x1f01;
+pub const GNU_str_index = 0x1f02;
+
+// Extensions for DWZ multifile.
+// See http://www.dwarfstd.org/ShowIssue.php?issue=120604.1&type=open .
+pub const GNU_ref_alt = 0x1f20;
+pub const GNU_strp_alt = 0x1f21;